To explore the hypothesized integrative function of corticotropin releasing hormone (CRH) in the stress response, stress-related behaviors including antinociception were studied in rats after either intracerebroventricular (ICV) or peripheral administration of CRH. The effects of low-dose (0.3 ωg) and high-dose (3.0 ωg) ICVCRH were compared to those of vehicle, employing a within- S design. The two doses yielded comparable behavioral changes suggestive of increased arousal and stress. These changes were characterized by significant increases in grooming, walking, burrowing, self-gnawing, and pica, and decreases in rearing and sleeping. None of these effects of ICVCRH were obtained with peripheral administration of the same doses. The hot-plate test of analgesia failed to show a significant effect of ICVCRH or peripherally administered CRH. A between- S experiment incorporating both the tail-flick and the hot-plate tests of analgesia compared ICVCRH (3.0 ωg) with vehicle. ICVCRH did not affect antinociceptive responding in either of these tests. In contrast, ICV morphine (10 ωg) yielded potent analgesia in both tests. Thus, with doses of ICVCRH yielding clear evidence of stress-related behavior, no evidence of analgesia was obtained. These findings question the possible role of central CRH systems in antinociceptive processes.